The FDA has approved trastuzumab-dkst as a biosimilar to trastuzumab for the treatment of patients with breast or metastatic stomach cancer (gastric or gastroesophageal junction adenocarcinoma) whose tumors overexpress the HER2 gene (HER2+). Trastuzumab-dkst is the first biosimilar approved in the U.S. for the treatment of breast cancer or stomach cancer and the second biosimilar approved in the U.S. for the treatment of cancer.
"The FDA continues to grow the number of biosimilar approvals, helping to promote competition that can lower health care costs. This is especially important when it comes to diseases like cancer that have a high cost burden for patients," said FDA Commissioner Scott Gottlieb, MD. "We're committed to taking new policy steps to advance our biosimilar pathway and promote more competition for biological drugs."
Biological products are generally derived from a living organism and can come from many sources, such as humans, animals, microorganisms, or yeast. A biosimilar is a biological product that is approved based on data showing that it is highly similar to a biological product already approved by the FDA (reference product) and has no clinically meaningful differences in terms of safety, purity and potency (i.e., safety and effectiveness) from the reference product, in addition to meeting other criteria specified by law.
The FDA's approval of trastuzumab-dkst is based on review of evidence that included extensive structural and functional characterization, animal study data, human pharmacokinetic and pharmacodynamic data, clinical immunogenicity data and other clinical safety and effectiveness data that demonstrates trastuzumab-dkst is biosimilar to Herceptin. Trastuzumab-dkst has been approved as a biosimilar, not as an interchangeable product.
Common expected side effects of trastuzumab-dkst for the treatment of HER2+ breast cancer include headache, diarrhea, nausea, chills, fever, infection, congestive heart failure, insomnia, cough, and rash.
Common expected side effects of trastuzumab-dkst for the treatment of HER2+ metastatic stomach cancer include neutropenia, diarrhea, fatigue, anemia, stomatitis, weight loss, upper respiratory tract infections, fever, thrombocytopenia, mucosal inflammation, nasopharyngitis, and dysgeusia. Serious expected side effects of trastuzumab-dkst include worsening of chemotherapy-induced neutropenia.
Like trastuzumab, the labeling for trastuzumab-dkst contains a Boxed Warning to alert health care professionals and patients about increased risks of cardiomyopathy, infusion reactions, pulmonary toxicity, and embryo-fetal toxicity. Patients should stop taking trastuzumab-dkst if cardiomyopathy, anaphylaxis, angioedema, interstitial pneumonitis, or acute respiratory distress syndrome occur.